1. Field of the Invention
The present invention relates to a pressure-sensitive adhesive (PSA) film, in particular, a PSA film preferably used for applications that involve cutting with a laser beam in a specific wavelength range.
2. Description of the Related Art
Techniques involving laser beam machining have been widely used for cutting and hole-making, etc., of various materials. Carbon dioxide laser is a typical example of a laser used for such machining processes. For instance, in an embodiment of such laser machining, a PSA film as an auxiliary material is adhered to a surface of a work piece and a laser beam is projected onto the PSA film, whereby the work piece along with the PSA film is processed with the laser. For example, Japanese Patent Application Publication No. 2004-235194 discloses a technique to increase hole-making reliability or workability, etc., by pressure-bonding an auxiliary PSA sheet to a copper-clad board and projecting a carbon dioxide laser onto the auxiliary PSA sheet to make holes in the copper-clad board.